Although there are numerous types of hand trucks or dollies, each type tends to fulfill only a specific, limited purpose. In contrast, the two-wheeled hand truck of the present invention is capable of multi-directional movement and allows an operator to move the hand truck forward and backward, side to side and about an axis of rotation through reconfiguration of the wheels on-the-fly by means of a trigger assembly.
Prior art patents include the device of U.S. Pat. No. 2,884,257 which is a two-wheeled hand truck peculiarly adapted for the display and transportation of outboard motors. In contrast to the multi-directional movement of the hand truck of the present invention, this device is only capable of forward and backward movement.
The device of U.S. Pat. No. 3,666,285 is capable of forward and backward and side to side movement, but is not capable of rotational movement. In contrast to the two-wheeled hand truck of the present invention which is capable of multi-directional movement, this device has two sets of wheels, a primary set of wheels for forward and backward movement and an auxiliary set of wheels for side to side movement. When one set of wheels is engaged and in contact with the floor, the other set is disengaged and lifted off the floor into a storage position. Furthermore, this device is not capable of rotational movement.
The device of U.S. Pat. No. 3,729,209 is capable of forward and backward and side to side movement, but is not capable of rotational movement. This device has two sets of wheels, a primary set of wheels for forward and backward movement and an auxiliary set of wheels used in conjunction with the primary set of wheels for side to side movement. This device is uniquely adapted for transportation of large long loads such as pool tables, bed springs or the like. In contrast to the hand truck of the present invention, this device is not capable of rotational movement.
The device of U.S. Pat. No. 4,003,584 is a trolley with four sets of articulated, steerable wheels that is of the particular type used in the cinema and television industries to carry a cinema or television camera together with the camera operator for the purpose of taking pictures while in motion. While this device is capable of multi-directional movement, each set of wheels is limited to operation in parallel; whereas, in contrast, the hand truck of the present invention may be moved with the independent wheels parallel to each other for forward and backward movement, in line with each other for side to side movement, or at various angles to each other for rotational movement.
The device of U.S. Pat. No. 4,460,189 is capable of forward and backward and side to side movement. The wheels of this device are semi-spherical in shape and redirection of the wheels is accomplished through manual repositioning of an indexing means. In contrast, the hand truck of the present invention allows for directional repositioning of the wheels through a range of motion of approximately 100 degrees by means of a handgrip and trigger assembly and is capable of forward and backward, side to side and rotational movement.
The device of U.S. Pat. No. 6,039,332 is capable of forward and backward and side to side movement, but is not capable of rotational movement. In this device, the wheels are indexed in parallel to allow for redirected movement of the hand truck and, in contrast to the hand truck of the present invention, the wheels are not capable of independent indexing.
The device of U.S. Pat. No. 6,450,514 is capable of multi-directional movement as accomplished through four caster wheels. Because the wheels are caster wheels, this device is not precisely steerable due to the independent movement of each wheel. In contrast, the hand truck of the present invention is precisely steerable through the positioning of the wheels in various stable indexing positions. Also, this device is particularly designed for transportation of large circular and rectangular sheets.
Lastly, the device of U.S. Pat. No. 6,663,120 is capable of forward and backward and side to side movement. Redirection of the wheels is accomplished through manual repositioning of an indexing means; whereas, in contrast, the hand truck of the present invention allows for directional repositioning of the wheels on-the-fly by means of a trigger assembly. Although this device is stated to be capable of rotational movement, it does not provide a precise, stable means for doing so, but rather relies upon frictional force to maintain the wheels in a non-precise, unstable intermediate indexing position for rotational movement. In contrast, the hand truck of the present invention provides for an indexing means that allows for positioning of the wheels in various precise, stable indexing positions to allow for rotational movement.